Stop sheep chasing the Alsatian? (3,2)
I believe the answer is:
let up
'stop' is the definition.
(I've seen this before)
'sheep chasing the alsatian?' is the wordplay.
'sheep' becomes 'tup' (tup is a kind of sheep).
'chasing' means one lot of letters go next to another (some letters chase after others).
'the alsatian?' becomes 'le' (I can't justify this - if you can you should give a lot more credence to this answer).
'tup' put after 'le' is 'LET-UP'.
Can you help me to learn more?
(Other definitions for let up that I've seen before include "Relax one's efforts" , "allowed out of bed?" , "Die away, ease off" , "stop" , "break" .)